Acknowledgements 1 Introduction 1 Francis Cheynell and Mid-Seventeenth-Century English Trinitarian Controversies 2 Puritan Piety 3 Method, Thesis, and Structure 2 Cheynell's Intellectual Biography and the English Crisis of Mid-Seventeenth-Century Reformed Trinitarianism 1 Introduction 2 Cheynell's Early and Pre-civil War Life 3 The 'Prevailing Faction' of Laudianism 4 The Rise of Socinianism 5 The 'Arch-Visitor' and Reformer 6 The Trinity: 'Not Problematical, but Fundamental' 7 Conclusion 3 Infinite Simplicity 1 Introduction 2 Divine Incomprehensibility: Chastening Human Reason 3 Divine Necessity: 'I Am That I Am' 4 How to Think and Speak about God Cautiously 5 Divine Simplicity and the Divine Attributes: What Kind of Distinction? 6 Conclusion 4 The Written Trinity 1 Introduction 2 The Trinity: The Authority of Tradition? 3 Trinitarian Exegesis Contra Radical Exegesis 4 The Biblical Portraiture of the 'Single and Eternal Godhead' 5 Conclusion 5 Unity in Trinunity: The Metaphysics of 'Nature' and 'Person' 1 Introduction 2 Cheynell's Reformed Scholastic Definition of Person 3 The 'Great Masters of Language' and Boethian Anti-Trinitarianism 4 The Nature-Person Distinction and the Transcendent Affections of Ens Simpliciter 5 Conclusion 6 Trinunity in Unity: The Metaphysics of Personal Distinction 1 Introduction 2 Cheynell's Reformed Inheritance of Medieval Trinitarianism 3 Divine Aseity and Essential Communication 4 'Natural' Communication in the Unity of the Divine Essence 5 The First Person A Se 6 Conclusion 7 The Mystery of Godliness: 'Divine' and 'Natural' Worship 1 Introduction 2 Intellectual and Affectionate Trinitarian Theology 3 Christ's Divine Nature: The Object of British and Continental Reformed Worship 4 British and Continental Kingdom Christology 5 Apocalyptic Communion with the Trinity 6 Conclusion 8 Conclusion Bibliography Index.